Field of the Various Embodiments
Embodiments of the present invention relate generally to display devices and display technology and, more specifically, to parallel pipelines for computing backlight illumination fields in high dynamic range display devices.
Description of the Related Art
A conventional liquid-crystal display (LCD) usually includes an array of light-emitting diodes (LEDs) coupled to an array of LCD pixels. The array of LEDs is commonly known as the “backlight.” In operation, the backlight emits light to the array of LCD pixels with a brightness that can vary across different LCD pixels. A given LCD pixel includes a set of filters that modifies the color of the light received from the backlight in order to emit light having a specific color value.
In a typical system, a display controller coordinates the operations of the backlight and the array of LCD pixels to cause an image to be displayed via the LCD. In so doing, the display controller determines the brightness of each LED included in the backlight based on the image to be displayed and then sets the current supplied to each LED to achieve the determined brightness. The display controller also configures each LCD pixel to emit light having a color value that represents a specific portion or pixel of the image being displayed. To configure a given LCD pixel to emit light having a specific color value, the display controller first estimates the total intensity of light received at the given LCD pixel from some or all LEDs included in the backlight. The display controller then divides the desired color value by that total intensity to produce percentages of red, green, and blue light the given LCD pixel should filter when displaying the image. Finally, the display controller configures the given LCD pixel according to these percentages.
When performing the above operations, the display controller usually estimates the total intensity of light received at a given LCD pixel by accumulating the individual light contributions from each LED to the given LCD pixel. Based on the accumulated light contributions, the display controller generates an entry in a backlight illumination field (BLIF) corresponding to the given LCD pixel. The light contribution from any given LED to a given LCD pixel can be estimated by evaluating a point-spread function (PSF). A PSF is a mapping that indicates the intensity of light at different distances from an LED. When computing an entry in the BLIF for a given LCD pixel, the display controller evaluates the PSF across all LEDs that contribute light to the given LCD pixel and then accumulates the results of those evaluations. The display controller performs these steps across all LCD pixels to fully populate the BLIF with a different entry for each LCD pixel. The display controller typically generates a new BLIF each time the LCD refreshes. Notably, this approach for generating BLIFs, is not feasible for certain types of display devices.
In particular, for high resolution display devices with densely populated backlights that operate at high refresh rates, the above computations have to be performed an excessive number of times in order to configure each LCD pixel. For example, in a 4K high dynamic range (HDR) display with a 24×16 matrix backlight operating at a 1440 Hz refresh rate, the display controller would need to evaluate the PSF approximately 300 billion times per second. Conventional display controllers simply do not operate not fast enough to complete all of the necessary computations and still maintain appropriate refresh rates. Consequently, conventional display controllers oftentimes make tradeoffs between computational accuracy and refresh rate when generating BLIFs for high resolution display devices. However, in specific high performance applications, such as gaming applications, sacrificing either computational accuracy or refresh rate can diminish the overall user experience.
As the foregoing illustrates, what is needed in the art are more effective techniques for computing BLIFs when configuring LCD pixels to display images.